Gymnocalycium denudatum (Cactaceae) Small globular usually unbranched cactus with glossy dark green body and rounded ribs. Grows up to 15 cm in diameter and 10cm tall. Nearly harmless spines flattened against body in shape of small, white spiders. Sowing : Sow seeds in summer in a well drained medium. Locality : Ex Hort. Date of harvest : March 2012.